Steam-heated and induction-heated rollers are used in the paper making, printing, paper, film, and foil converting industries. Some examples are: web heating rollers, drying rollers and drums, laminating rollers, embossing rollers, and cast film extrusion rollers.
Internally heated fuser rollers are used in the copier industry. The fuser roller melts the toner and presses it into the paper. The typical fuser roller consists of an aluminum or non-magnetic metal core with an internal quartz heating lamp. The inner diameter of the core has a special coating to absorb heat from the lamp. The roller is coated with a non-stick elastomeric material (e.g. silicone rubber) to provide a pressure nip with an opposing roller and to release the toner to the paper.
Heating rollers for xerography and other applications are disclosed in the following U.S. Patents, Satomura, No. 4,628,183; Nagaska, et al., No. 4,743,940; Lee, et al., No. 4,791,275; Kogure, et al., No. 4,813,372; Urban, et al., No. 4,810,858; Urban, No. 4,820,904, Yoshikawa, et al., No. 4,841,154; Landa, et al., No. 5,089,856.
There is a technical problem in controlling the heat within the roller under varying and continuing operating conditions, so that the roller does not become overheated, particularly in the area of the operating surface, and the desired temperature is maintained.
The present invention is directed to improved constructions of heater rollers for controlled heating of the heater roller under various operating conditions.